Oil blast circuit breaker



Nov. 12, 1935. w. A. COATES 2,020,995

OIL BLAST CIRCUIT BREAKER Filed Jan. 5,, 1934 23 Inventov:

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Patented Nov. 12, 1935 on. BLAST cmcuir BREAKER William Anselm Coates, Bowdon, England, asslgnor to General Electric Company, a corporation of New York Application January 5, 1934, Serial No. 705,448

.In Great Britain January 18, 1933 9 Claims.

This invention relates to electric switches or circuit breakers of the fluid-blast type wherein the switch contacts are immersed in an insulating fluid, as oil, and arranged to provide a plurality of breaks in series, the are where the circuit is actually to be broken being extinguished by a blast of oil produced by pressure generated by a preliminary or pressure-generating are occurring between auxiliary contacts within an 10 explosion pot.

When such a switch is employed for breaking small currents, for example at, very high voltage, the pressure-generating are formed between the auxiliary contacts may not produce sufficient enl5 ergy to cause an eifective oil blast for extinction of the main arc, while the voltage may be high enough to enable the arc to persist unless it is extinguished at an early stage of its formation.

A principal object of the present invention is theprovision of an improved circuit breaker of the aforesaid type which shall be simple in construction and reliable, positive and eilicient in operation.

According to the present invention a plurality of preliminary or pressure-generating breaks in series are caused to occur simultaneously in the explosion pot so that the oil blast is directed by sufficient pressure to extinguish the arc occurring on the final break.

This invention will be more fully set forth in the following description referring to the accompanying drawing, and the features of. novelty which characterize the invention will be pointed out with particularity in the claims annexed to 85 and forming a part of this specification.

Referring to the drawing, Fig. 1 is an elevational sectional view of oil-blast, explosion-pot circuit breaker structure embodying the present invention; Fig. 2 is a reduced plan sectional view 40ftakenalong the line II-II of Fig. 1; Fig. 3 is a reduced plan sectional view taken along the line I II-III of Fig. l; and Fig. 4 is a similar view of another form of my invention.

In carrying out the invention according to a 46 preferred arrangement thereof the preliminary or pressure-generating breaks in the circuit may be arranged to occur in a single closed vessel or explosion pot filled with oil, and the rise in pressure due to the arcs formedtherein causes flow 50 of oil from said explosion pot through a passage adjacent the place where the final break in the circuit occurs, the oil flow being preferably across the arc in the form of a multiple jet.

It will be understood that the explosion pot as arrangement shown in Fig. 1 will be located in an oil tank and rigidly mounted, such as upon the main terminal lead-in conductor I, usually side by side with another similar arrangement (not shown). The two explosion pots are arranged to be interconnected by a moving bridge 5 (also not shown) which has a pair of upstanding rod or plug contacts, one of which is shown at 2 in the open circuit position. The plug 2 in order to close the switch is adapted to travel through a vertical passageway indicated at 3 10 which is intersected by a plurality of transverse passageways 4 which, along with the passageway 3, are formed in insulating material in generally known manner. At their right hand ends as viewed these, passageways 4 communicate with 15 an opening 5' in an outer insulating cylinder 6 and at their left hand ends they communicate with a vertical channel 1. The passageways 4 are bounded at the top by an insulating member 8 and at the bottom by another insulating mem- 20 ber 9.

For the purpose of obtaining a multiplicity of breaks in series the contacts which are first separated when the circuit is to be interrupted are constructed so that when the contacts are in 2! engagement the current passes backwards and forwards from one contact to another a number of times whereby when the contacts are separated a number of comparatively short breaks will occur in the circuit in series. As the amount 8( of heat energy transferred to the oil by the arc is dependent upon the length of the are as well as the current it will be seen that by the present arrangement the total length of the arc is increased in proportion to the number of prelimi- 3i nary breaks although the current carried by the arc may be small. The path of the current from contact to contact may be non-linear, that is in the form of a zigzag, or may form a series of closed loops.

In some cases the component parts or pairs of the contacts between which the arcs are formed may be spaced apart in a graduated manner, in which case with larger currents some of the arcs which are located closely adjacent to each other will coalesce. This isa desirable feature as the pressure available for directing the oil blast will be graduated to some extent automatically. If the pairs of series of contacts are spaced apart in a progressively increasing manner, for example, individual arcs will be formed between the pairs of contacts when very small currents pass, while two or three or more of the arcs may coalesce when a larger current passes, thereby automatically reducing the arc pressure at large or short circuit currents.

The moving contact 2 is adapted to engage a main contact in which is carried on a rod I I vertically slidable with respect to the insulating member 8. The rod I I is secured at its upper end to a carrier 12 for a plurality of movable auxiliary contacts which cooperate with a corresponding number of fixed auxiliary contacts. The auxiliary arcs are formed in series before the moving contact 2 separates from the fixed contact i0 between which the final or main arc is drawn, the are being quenched by the blasts of oil or a mixture of gas and oil flowing through the transverse passageways 4 from the vertical channel I from the upper explosion pot or chamber I3 in which the aforesaid series preliminary arcs take place. It is to be understood that since the arrangement shown in Fig. l is immersed in oil its interior will be normally full of oil so that the oil in the upper explosion pot II will be forced therefrom by the preliminary arcs.

The fixed contacts for the preliminary arcs in the arrangements shown are seven in number and are indicated respectively at ll to 20, inclusive, as will readily be seen from Fig. 2, but two thereof, I4 and I B, being visible in Fig. 1. The

contact H is connected by means of a radial conducting strap 2l with a central conductor 22 which is connected with the main terminal conductor I. The contacts I! and I6 are connected by a tangential strap 23. The contacts H to 20, inclusive, are likewise connected in pairs by conducting straps 23. The contacts H to 20 and the members 2|, 22 and 23 are conveniently moulded in a block 24 of insulating material such as a phenolic condensation product. The contacts I! to 20 are preferably exposed at the upper ends of respective recesses 25 in the insulating block 24. The angles between the pairs of contacts Hl5, i5- l6 l9-20 may be equal, as shown, or they may be graded as and for the purpose hereinbeiore set forth. Fig. 4 illustrates such an arrangement, the movable contacts 26 to 32 inclusive, and the corresponding stationary contacts (not shown) being spaced so that some ol' the more closely positioned arcs are short-circuiteci at heavy currents and the arc length and pressure accordingly reduced.

The moving auxiliary contacts are indicated at 26 to 32, inclusive. ili'liey are formed or provided with stem portzons 331'; slidable in holes in the upper portion of the carrier i2 which is made in two parts adapted to be rigidly secured together, the upper of which is shown at 34 and the lower portion thereof at 35. These portions 3| and 35 may also be made of moulded insulating material. The upper portion 34 is also provided with tubular guide portions 36 for the contacts 26 to 32 and also with recesses 31 on the under side to accommodate heads 38 on the stems 33. The recesses 3? are connected in consecutive pairs by linking channels 39, as indicated by dotted lines in i, 3. The recess 31 for the contact 32 has i linking channel 40 communicating with the up; er and of the contact ll. Within these channss .5) and 10 are accommodated conductors ll, :nly parts of two of which are visible in Fig. i, for connecting together respectively the moving auxiliary contacts 26 and 2], 2i and 29, 30 and 3t, and the contact 22, and the main contact iii. The contacts 26 to 32 are biased upwards with respect to the carrier l2 by means of springs 42.

A spring 43 is interposed between the main contact II and the upper end of a recess N in the insulating member I, the arrangement being such that the carrier I2 is normally retained by the spring 42 in the lower position illustrated, but is capable of being raised by the moving main con- 5 tact 2 when the latter engages the coacting contact ll, until the contacts 28 to 22 engage respectively the contacts ll to 20, the contacts 28 to 32 moving as necessary, relatively to the carrier l2 by reason of the biasing springs l2. 10

With the arrangement described it will be appreciated that current fiowing down the main terminal conductor I will, as indicated by the short arrows in Fig. l and by Figs. 2 and 3, fiow from the member 22 first down through the fixed 15 contact II to the contact 28, upwards through the moving auxiliary contact 21, the fixed contact ii, the strap 23, the fixed contact it, downwards'to the moving auxiliary contact 2| and so on and finally from the moving contact 22 to the 20 main contact l0 and the main moving contact 2. Upon the opening of the circuit breaker it will be appreciated that by reason of the arrangement, the pairs of auxiliary contacts 2l|l, 2IIi I22l will separate simultaneously 25 before the contacts 2 and I8 start to separate, and the Joint effect of the seven preliminary arcs in the chamber II will cause a powerful. blast of oil to flow, as indicated by the chain i he arrows in Fig. 1, from this chamber down the 5% channel 1 and through the cross Jet passages 4 so as to be efiective in quenching the arc be tween the main contacts 2 and ll in the vertical passage 8.

In a convenient constructional form of the invention the bottom of the explosion pot through a passage in which the movable contact of the switch is arranged to move when making and breaking the circuit may comprise a series 0! plates spaced apart so as to form transverse passages through which a flow of oil or oil and vapor is caused by reason of the pressure arising in the explosion pot. These arrangements are well known and various constructional'forms have been employed. The switch contacts for obtaining the several preliminary breaks in series and the connecting members of these contacts may be embedded in and insulated as necessary from each other by a suitable insulating material moulded to suitable form. 5 It should be understood that this invention is not limited to specific details of construction and arrangement thereof herein illustrated, and that changes and modifications may occur to one skilled in the art without departing from the 5 spirit of my invention.

What 1 claim as new and desire to secure by Letters Patent oi. the United States, is:-

1. An electric circuit breaker of the oil-blast type for interrupting high tension power circuits, 50 comprising means forming a chamber containing an insulating liquid, relatively movable contact structure in said chamber including means forming a plurality of breaks in series at which preliminary pressure-generating arcs are formed, and means forming exteriorly of said chamber a main arc in series with the aforesaid arcs, the presure generated by said preliminary arcs combining to direct a blast of insulating liquid from said chamber across said main arc. 7

2. An electric circuit breaker of the oil-blast type for interrupting high tension power circuits, comprising an explosion chamber pot .zontaining an insulating liquid, relatively movable contact structure disposed within said pot including a 7 aforesaid contacts between which the arc to be interrupted is formed, and means directing the combined pressure of said pressure-generating arcs so as to cause a blast of insulating liquid through the pot.

3. An electric circuit breaker of the oil-blast type, comprising means forming an explosion chamber, an arc-extinguishing liquid within said chamber, relatively movable contact structure disposed within said chamber including pressuregenerating contacts, and main current-interrupting contacts connected in series with the aforesaid contacts, said current-interrupting contacts subjected to a blast of said liquid from said chamber in response to generation of arcing pressure therein, said pressure-generating contacts including a plurality-oi pairs of contacts unequally spaced with respect to each other so that there is a tendency on the part of large arc currents to short circuit one or more oi the pressure-generating arcs.

4. An electric circuit breaker of the oil-blast arc to be interrupted and from said type, comprising means forming an explosionchamber, insulating liquid within said chamber, relatively movable contact structure disposed within said chamber including a plurality oi pairs of contacts connected in series for producing pressure in said chamber, and contacts connected in series with the aforesaid contacts for interrupting the current, said pairs of pressure-generating contacts being arranged in said explosion chamber so that the total length of the pressure-generating arc is automatically shortened at heavy currents and so that the combined pressure in said chamber so as to cause a blast oi arcextinguishing liquid through said main arc.

6. An electric circuit breaker oi the oil-blast type for interrupting high tension power circuits, comprising an explosion chamber pot, an insulating liquid filling said pot, relatively movable contact structure disposed within said pot comprising a movable rod contact, an intermediate butt contact, a plurality of contacts carried by and movable with said intermediate contacts. a

plurality of coacting stationary contacts arranged to form with said movable contacts a plurality of breaks in series, said pairs oi. contacts disposed in a single pressure-generating chamber in said pot, and means directing the pressure from said chamber so as to cause a blast of insulating liquid from the same and through the arc formed between said intermediate and rod contacts.

7. An electric circuit breaker of the oil-blast type, comprising means forming an explosion chamber, an insulating liquid filling saidcham ber, relatively movable contact structure for generating arcing pressure in said chamber and for forming a main are subject to a blast oi insulating liquid from said chamber including a movable rod contact, an intermediate contact, a plurality of contacts carried by and movable with said intermediate contact, said plurality of contacts arranged generally in a circle, a plurality of coacting stationary contacts positioned in a corresponding manner and arranged to form with said movable contacts a plurality of breaks in series, said pairs of contacts disposecl'in said chamber and positioned in varying angular relationship so that one or more of said pairs are short circuited by heavy arc currents, and means directing the pressure from said chamber so as to cause a blast of insulating liquid through the main are formed between said intermediate and rod contacts.

\ 80 8. An electric circuit interrupter oi the fluidblast type for high tension power circuits, comprising means for causing arcing and generation of pressure within an arc-extinguishing fluid in the circuit opening operation,saidmeansnorrnally forming an appreciable arc length for generating pressure at low current values, said means arranged so that-shortenlng oi! the are by short circuiting of a part of the same takes place at comparatively high current values, means form- 0 ing another are in said circuit, and means for directing said pressure so 'as to cause a blast of arc-extinguishing fluid through said last-named arc.

9. An electric circuit breaker of the fluid-blast 5 type for interrupting high tension power-circuits, comprising relatively movable contact structure for causing arcing and the generation or pressure within an arc-extinguishing fluid in the circuit opening operation, said contact structure normally forming an appreciable arc length for generating pressure at low current values and. arranged so that said contact structure is short circuited in part by the arc current at comparatively high current values for reducing said arc length, means forming another are in said circult, and means for directing said pressure so as to cause ablast of arc-extinguishing fluid through said last-named arc.

' WILLIAM ANsaLM coA'ms. 

